We will continue all patients remaining in the Special Action Office for Drug Abuse Prevention Comparative LAAM-Methadone study from May 1, 1975 until they complete their forty weeks or terminate early. Those wishing to continue in the study and deemed suitable will enter the Vanguard Study upon completing the parent study. They may change drugs, either from LAAM to methadone or vice-versa if they choose. We hope to have twenty-two patients complete Vanguard. We will perform the monthly evaluations called for in the protocol. In the Vanguard study, these evaluations will be performed bimonthly instead of monthly. Study forms will be done and submitted to the cooperative studies center as required. We will recruit 5 women not of child-bearing potential and five matched controls. The former will take LAAM; the latter, methadone under the same terms as the parent study with monthly evaluations as required for the men. Additionally, breast and pelvic examinations and pap smear and maturation index will be done as prescribed by the protocol. Verification of sterility will be through hospital records and/or gynecological consultation as necessary. Study forms will be filled out and submitted as required MMPIs will be done on all patients.